If you want be healthier and eat for less, than eat like the poor. No I'm not talking about American poor, the great unwashed masses of obesity. I'm talking about the truly poor. What is the common diet of Bolivians? How about India? What do they eat in SE Asia? Rural Chinese cuisine anyone?
It should also be noted that these are some of the healthiest people on the planet. The problem is their longevity is skewed due to diseases that have been eradicated in Western societies for a few generations now. In order to not breed ignorance you should read these three books: THE BLUE ZONES, HEALTHY AT 100, and THE CHINA STUDY.
They look at pockets of societies where people live very long and just so happen to be quite poor. Coincidence?
Their diets revolve around these staples: fruits, veggies, nuts, rice, spices, small amounts of lean meat (usually fish), beans, and eggs. Most of these items are eatin raw (heat costs money) except for obviously rice, beans, and the meat. However, the rice and beans can actually be "cooked" using no heat via soaking. Google it, it's also healthier.
On top of this, mimic the poors physical activity. THEY WALK EVERYWHERE! Not because they like it, but because it's free. Walk to the grocery store. Walk to the farmer's market. And if you're going to eat crap fast food at least walk there as well. A simple rule is that if you're going to eat, then you have to expel some calories in order to get it, just like the cavemen.
The USA is the only place I've seen where there are obese homeless people. This would lead one to think that food here is cheap. Food here is cheap, but relative to what you can get at the grocery store processed fast food is still quite expensive.
I haven't explored the dietary rituals of the homeless, but I would suspect that for their own safety they're eating out of McDonald's dumpsters and not the raw organic coop. Processed food kills you one bite at a time. And your wallet one dollar a purchase.